Field of the Invention
The present invention relates to an anti-vibration wheel for an automobile and more particularly, to an anti-vibration wheel for an automobile to improve riding comport by attenuating noise and vibration from the surface of a road during the driving of the automobile.
Description of the Related Art
In general, automobile wheels are made of steel or aluminum. This kind of a wheel is secured to a wheel hub having a brake drum or a brake disc by a round head screw or conical head screw.
To improve the fuel-efficiency of an automobile by decreasing the weight of the automobile, aluminum which is a light material has been used for an automobile wheel. Further, a technology to structurally lighten the weight has been also developed.
Usually, when a wheel is designed, it is considered to primarily satisfy the strength requirements. The structures, such as the thicknesses and designs of a hub mounting portion and a spoke portion of a wheel, have been designed to satisfy the minimum required strength of the wheel. Then, a process for secondary weight lightening (decrease of weight) has been performed inside the hub mounting portion and the spoke portion of the wheel to improve the fuel-efficiency.
However, as the wheel weight has been lightened through the aforementioned ways, the stiffness becomes insufficient, causing vibration and noise of the wheel during the driving of the automobile. To prevent these problems, casting thickness is again provided inside the hub mounting portion and the spoke portion of the wheel. Even the entire shape of the wheel is thickened, thereby increasing the unnecessary stiffness rather than the minimum required strength. This again increases the weight and therefore, it restricts the improvement of fuel-efficiency.
Korean Patent Published Application No. 10-2006-0044653 (hereinafter referred to as ‘Reference 1’) discloses a technology to decrease weight and block noise by forming a hollow chamber in a rim. The technology of forming the hollow chamber in the rim and spokes is disclosed in not only Reference 1 but also Korean Patent Published Application Nos. 10-2007-0053386 and 10-1999-0062973. The method of forming the hollow chamber has the effect of reducing weight and absorbing noise but it has a problem in that durability is weakened.
Korean Patent Published Application No. 10-2007-0053386 (hereinafter referred to as ‘Reference 2’) discloses a technology to absorb noise and vibration by forming a hollow chamber in a rim and filling it with an aluminum foam core. The technology of forming the hollow chamber in the rim and spokes and filling it with the foam core has a better effect of absorbing noise in comparison with Reference 1 but a less effect in reducing weight.
As shown in FIG. 1 and FIG. 2, the conventional wheel for an automobile includes a disk member 2 with a rim member 3 extending in one direction from the outer circumferential edge of the disk member 2. A tire 1 is mounted on the outside surface of the rim member 3. That is, the tire 1 includes an outer bead 1a in its one end and an inner bead 1b in its other end. The outer bead 1a is secured at an outer bead seat 3a of the rim member 3 forming the outside of the disk member 2. The inner bead 1b is secured at an inner bead seat 3b formed at a free end of the rim member 3.
In the rim member 3, a well portion 31 extending from the outer bead seat 3a protruding from the disk member 2 is formed to be different from the inner bead seat 3b in thickness. The well portion 31 includes an outer well portion 31a and an inner well portion 31b. The outer well portion 31a extends from the outer bead seat 3a. The inner well portion 31b is offset and inclined from the outer well portion 31a outward. The inner bead seat 3b extends from the inner well portion 31b. 
The thickness of the well portion 31 and the thickness of the inner bead sheet 3b are formed differently. The thickness C of the inner bead seat 3b where the inner bead 1b of the tire 1 sits is greater than the thickness A of the outer well portion 31a, which extends from the outer bead sea 3a protruding from the disk member 2, which is greater than the thickness B of the inner well portion 31b between the outer well portion 31a and the inner bead seat 3b (C>A>B).
The above-mentioned conventional wheel for an automobile receives the load corresponding to the weight of the automobile through the surface of a road during the driving of the automobile. The loads F1, F2 transferred to the wheel are transferred through the both beads 1a, 1b of the tire 1 as shown in FIG. 2.
However, as shown in FIG. 2, the loads F1, F2 transferred through the tire 1 are applied to the outer bead seat 3a of the rim member 3 through the outer bead 1a of the tire 1 and the inner bead seat 3b of the rim member 3 through the inner bead 1b of the tire 1, respectively. In the outer bead seat 3a and inner bead seat 3b of the rim member 3, reaction forces R1, R2 thereto act, respectively.
Specially, the reaction force R2 to the load F2 applied to the inner bead seat 3b of the rim member 3 acts as being transferred to reaction force R2′ of the outer well portion 31a which has one end fixed to the disk member 2 and therefore which functions as a cantilever.
Therefore, as for the load F1 applied to the outer bead seat 3a, the reaction force R1 acts straightly in the opposite direction to the load F1, playing a role of action and reaction. However, as for the load F2 applied to the inner bead seat 3b, since the reaction force R2 to the load F2 is transferred to the reaction force R2′ of the outer well portion 31a to act, the amount of deformation ε1 occurs in the inner bead seat 3b. Since the thickness A of the outer well portion 31a is relatively thinner than the thickness C of the inner well portion 31b and therefore the support surface as a fixed end is small, the deformation is generated from the fixed end of the outer well portion 31a and therefore the amount of overall deformation ε1 is big. The vibration corresponding to the amount of deformation ε1 is transferred to a hub (not shown) of the automobile through a spoke portion 22 of the wheel, to generate vibration and noise of the automobile as they are.
Korean Patent Published Application No. 10-2006-0044653 (hereinafter referred to as ‘Reference 1’) discloses a technology to decrease weight and block noise by forming a hollow chamber in a rim. The technology of forming the hollow chamber in the rim and spokes is disclosed in not only Reference 1 but also Korean Patent Published Application No. 10-2007-0053386 and 10-1999-0062973. The method of forming the hollow chamber has the effect of reducing weight and absorbing noise but it has a problem in that durability is weakened.
Korean Patent Published Application No. 10-2007-0053386 (hereinafter referred to as ‘Reference 2’) discloses a technology to absorb noise and vibration by forming a hollow chamber in a rim and filling it with an aluminum foam core. The technology of forming the hollow chamber in the rim and spokes and filling it with the foam core has a better effect of absorbing noise in comparison with Reference 1 but a less effect in reducing weight.
The aforementioned automobile wheels and the technology thereof are discussed in detail in 1: Korean Patent Application No. 2006-0044653; 2: Korean Patent Application No. 2007-0053386; and 3: Korean Patent Published Application No. 10-1999-0062973. These publications are hereby incorporated by reference in their entireties into this application to fully illustrate the state of the art.